The present invention relates to an airtight-type electric motor used in a very low temperature freezer, for example.
A conventional airtight-type electric motor is disclosed in Japanese Patent Application Publication No. 2001-280501 (JP2001-280501A) or the like. The conventional electric motor comprises a rotor having a shaft, a stator including a stator core arranged radially outside of the shaft and a plurality of winding portions, and a cylindrical housing. The cylindrical housing surrounds the stator and is arranged radially outside of the stator. The shaft is rotatably supported by a pair of end brackets through a pair of bearings. In the airtight-type electric motor in particular, the housing serves to ensure pressure resistance and airtightness. The housing is connected to the pair of end brackets by fitting means or the like. An outer circumferential surface of the stator core is fixed to an inner circumferential surface of the housing by adhesive.
In the airtight-type electric motor of this type, reduction of vibration of the electric motor caused by rotation is demanded. However, in such an airtight-type electric motor, there is a limit to reducing the vibration of the electric motor.
Further, in the conventional airtight-type electric motor, when the stator core is fixed to the housing, the stator core must be pushed in or bonded inside the housing. For this reason, after the stator core has been fixed to the housing, the winding portions are formed. For formation of the winding portions, insulators with electric wires wound therearound are fitted with the stator core, or after an insulator has been fitted with the stator core, the electric wires are wound around the stator core through the insulator. In both cases, however, connection of electric wire ending portions after the electric wires have been wound must be manually performed due to presence of the housing.